Activation of ventral CA1 hippocampal neurons projecting to the lateral septum during feeding.
Hippocampus
; 31(3): 294-304, 2021 03.
Article
em En
| MEDLINE
| ID: mdl-33296119
ABSTRACT
A number of studies have reported the involvement of the ventral hippocampus (vHip) and the lateral septum (LS) in negative emotional responses. Besides these well-documented functions, they are also thought to control feeding behavior. In particular, optogenetic and pharmacogenetic interventions to LS-projecting vHip neurons have demonstrated that the vHipâLS neural circuit exerts an inhibition on feeding behavior. However, there have been no reports of vHip neuronal activity during feeding. Here, we focused on LS-projecting vCA1 neurons (vCA1âLS ) and monitored their activity during feeding behaviors in mice. vCA1âLS neurons were retrogradely labeled with adeno-associated virus carrying a ratiometric Ca2+ indicator and measured compound Ca2+ dynamics by fiber photometry. We first examined vCA1âLS activity in random food-exploring behavior and found that vCA1âLS activation seemed to coincide with food intake; however, our ability to visually confirm this during freely moving behaviors was not sufficiently reliable. We next examined vCA1âLS activity in a goal-directed, food-seeking lever-press task which temporally divided the mouse state into preparatory, effort, and consummatory phases. We observed vCA1âLS activation in the postprandial period during the consummatory phase. Such timing- and pathway-specific activation was not observed from pan-vCA1 neurons. In contrast, reward omission eliminated this activity, indicating that vCA1âLS activation is contingent on the food reward. Sated mice pressed the lever significantly fewer times but still ate food; however, vCA1âLS neurons were not activated, suggesting that vCA1âLS neurons did not respond to habitual behavior. Combined, these results suggest that gastrointestinal interoception rather than food-intake motions or external sensations are likely to coincide with vCA1âLS activity. Accordingly, we propose that vCA1âLS neurons discriminate between matched or unmatched predictive bodily states in which incoming food will satisfy an appetite. We also demonstrate that vCA1âLS neurons are activated in aversive/anxious situations in an elevated plus maze and tail suspension test. Future behavioral tests utilizing anxious conflict and food intake may reconcile the multiple functions of vCA1âLS neurons.
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MEDLINE
Assunto principal:
Região CA1 Hipocampal
/
Hipocampo
Limite:
Animals
Idioma:
En
Ano de publicação:
2021
Tipo de documento:
Article